Efficient Synthesis of 4,4'-(Arylmethylene)-bis(3- methyl-1-phenylpyrazol-5-ol) Derivatives in PEG-400 under Catalyst-free Conditions

摘要

Pollution control demands are a source of inspiration to design and develop new reaction mediums to achieve high efficiency. Much attention has been directed toward the development of environmentally benign syntheses, including the use of sol vent-free conditions, and application of solvents such as ionic liquids or water. These protocols have been successfully used to achieve various chemical transformations, but there are some disadvantages that limit the use of these procedures. For example, in many organic reactions, solvents play a critical role to promote more efficient molecular interactions, but most organic compounds are not soluble in water. Moreover, due to the sensitivity of many catalysts to aqueous conditions, the use of water as solvent is limited to some special reactions. Ionic liquids also require tedious preparation and their environmental safety is still debatable.